Cyclopentanone derivatives such as Hedione® (methyl 3-oxo-2-pentyl-1-cyclopentaneacetate; origin Firmenich S. A.), methyl 3-oxo-2-(2-pentenyl)-1-cyclopentaneacetate (methyl jasmonate) or methyl 3-oxo-2-pentyl-1-cyclopentene-1-acetate, are very important ingredients of the perfumery industry. Consequently, there is a need for new intermediates, and processes for their preparation, which can be advantageously employed in the synthesis of the above-mentioned perfuming ingredients.
In the literature there is no report, nor suggestion, of a process for the synthesis of a 2-alkylidene-3-oxo-cyclopentylacetate derivative, as defined below, involving the rearrangement of, a 2-(1-hydroxyalkyl)-cyclopent-2-en-1-one derivative as reported below.
Moreover, amongst the final compounds of the invention's process only methyl 3-oxo-2-pentylidene-cyclopentaneacetate is known in the prior art (S. Shicheng et al. in Youji Huaxue, 1986, 6, 453-6). However, said compound has been obtained by a process totally different from the one of the present invention. Furthermore, the 2-(1-hydroxyalkyl)-cyclopent-2-en-1-one derivative, as defined further below, have not been reported or suggested in the literature.